Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board 1970 Lightning "Y" Bike Project...

Sourcing a proper front end would be very beneficial, brake is much more effective than what you have now. I just found out is much better than my stock disc brake on my 73 T 150.
The same with forks, I like them better than my 73 Trident forks.

Hi Adam,


More work needed on the disc brake?

Regards,

Yes, comparing stock to stock BSA drum wins ( not taking into consideration much higher weight of the Trident ).
I already started improving it by changing stock pads to Ferodo Platinum, which under a touch feel 10x more abrasive than stock.
However I still can't try it, as I'm waiting on valve adjusters from Gale Gorman who agreed to send them free of any charges which is very generous.
Unfortunately I had two cases of dropped pushrod, one caused by pinch rocker box spring and one of them caused partially thread removal from one of the adjusters.

It was a good day walking around Kempton Jumble today, I managed to get a few things for the Lightning, so I can now start to get this thing headed back towards the road.
The first things on my list were the handlebars, and the Lucas rear light, well as you can see I found some new Triumph western style bars, and I also found a genuine Lucas rear light unit. These two items alone have transformed the look of the bike.

Before..


After..









I have new gaiters to fit, new fuel taps, and fuel line. but first tomorrow I will be pulling the head to see what the top end looks like. :bigt

People are strange when you're a stranger
Faces look ugly when you're alone
Women seem wicked when you're unwanted
Streets are uneven when you're down

When you're strange
Faces come out of the rain
When you're strange
No one remembers your name
When you're strange
When you're strange
When you're strange

So said the Doors.... And in some cases it seems to be true, especially when you start looking at old bikes that have an unknown history, and just when you think you have seen it all, up pops something new that makes you chuckle to yourself, whilst at the same time makes you recoil in disbelief as you wonder what other little surprises await as you dig further into that "new" old bike!

Today I started pulling the top end apart to try to discover the cause of low compression on one cylinder, so the first thing that needs removing is the tank, which as had already been noted had the wrong fuel taps fitted....



but what I discovered here left me speechless, in an amused bewildered sort of way!







Yes, that is an ariel coaxial cable joining piece!

So the previous owner was a cable guy huh?
That's a strange approach to mounting petcocks, don't know how people arrive at decisions like that.

Kev... you need a passenger grab rail.

Don in Nipomo

Tank off, and deeper in to the mire...

Original Lucas harness.







pistons are at +20, and there is evidence of previous problems. as this light scoring proves, but this looks worse in the picture than it actually is, you can't feel it with your finger nail, so a light honing should be fine here.





Valves seem to be sealing well, but will be removed, later for head overhaul. So that only leaves one place for the compression loss, it must be the rings?



And that proves to be true when the barrels are removed, and we find that all the rings are solidly stuck in, on the R/H piston, causing blow by, on this cylinder. Time to order some new rings.

Kev, did the bike come with a head stay?
I haven't spotted one yet.

Don in Nipomo

Unstick the rings by heating the piston crown with a heat gun, then slapping a wet cloth on to chill, repeat till the rings pop out. They may even be reusable if they aent too corroded.

No Don, missing in action?

:bigt

Too corroded, pistons are salvageable so shall just find some rings..

:bigt

I love a good project.

Kev, those types of Pistons (with the cut always that look like something of Dr Who) were prone to cracking and dropping the skirt. I would Suguest looking at fitting a set with the 3 small oil control holes for and aft of the piston to prevent problem in the future.

A hone may fix your problem. Are you doing it your self or sending it in?

Agreed, or see how poorly the same TLS on the pre OIF A65 is compared when fitted to a Rocket3

Hi Allan,


Mmmm ... my T150 has one and, while I wouldn't choose the drum over a disc if, say, descending an alp two-up with camping gear, and it fades about two-thirds of the way through a race-track 'parade' - usually on Steep Drop Hill into Squeaky Bottom Bend - on the road it should do what it says on the tin without drama, especially if anyone's done the usual match the shoes to the drum, adjust the shoes correctly, etc., etc.

Regards,

just re read my statement, made it sound like it was better with the heavier bike.

On my A65, I had the drum skimmed and over sized shoes fitted to suit. once it started to bed in it has a real good bite, too good infact so when I use the brake its only at limited pressure. I set my friends rocket3 up the same and the only difference being the brake light switch mid cable (I dont think this helps at all) Whether the weight of the bike is enough to overcome the wanting to lock the brake. But I would personally prefer the T140 or T160 disc brake conversion. And if those brakes arent powerful enough then Norman Hyde does a twin disc conversion. He also does a floating disc arangement too... A lot of pretty add-ons to be had if your willing to spend the cash.

So you own a bike owned by Larry the Cable Guy, petcock problems?, GIT-R-DONE. Pretty decent looking bike for being 46 years old.

+ 1 to Allan post about the pistons.
Buy yourself a very decent set of JCC pistons ( $ 100 a pair on Ebay.com )+ good Goetze rings from Walridge ( Canada )for cheap as well and be done with cylinder / pistons problem for the next 20 years .
Same with the head, stock stuff is too low quality to work longer than 2 years, Kibblewhite valves and guides give you much longer service.
They are expensive, so to make it little cheaper you can go with iron guides - they work well with those valves. Had them in my engine for 3 years.

To the brake part discussion my take is as follows :
- over sized shoes and skimmed drum is the beginning - the shoes have to be arc to the drum,
- the slider's tang should be tight in the brake plate.
Those gave me 2 finger brake with solid bite at the beginning of braking.
Reading through early T150 tests, opinions about front TLS brake were mostly favorable.
This info about could be relevant for Kevin in the future

Doing it myself Allan.... :bigt

I wouldn't use those pistons either, nothing but trouble...





You're going to need a headstay, besides the obvious advantage of keeping your engine from bouncing around in the frame you need it to mount the horn relay.


Don in Nipomo

Deciding which pistons to use is a lottery when buying from the internet or online shop, most places now use a generic picture of a piston, not a specific piston, and in some cases not even a BSA piston? I had in mind to fit a lower compression set at this time, but they seem to be double the price of the standard 9-1 compression kits, I have no idea why. So I have ordered a set of +20's from a well known supplier over here in the UK. We shall see what I get.

I am not too concerned over the whole front end fork thing, if I was into restoring the bike then maybe, but I am only building a general rider, so as long as it is clean and reliable, I will be happy, and then I may put things "right" at a later date, if I feel the need.

Just trying to pass my experiences about this bike ( my is 70 Thunderbolt ) learned during 8 years of ownership in the "school of hard knocks". How do you use it, it's your business.
I wrote about front end + TLS brake, because it makes general rider from this bike for me.

Hi Adam, I hope I didn't come across as ungrateful, far from it, I really appreciate all the input I have received in this thread.

:bigt

Rereading my answer again feels snappy, but it wasn't my intention.
Everybody has his own circumstances and experiences shaping his actions.
Canada is very different from GB and what could be natural here is probably not there.
Good luck with your project.

Here is a question for the rivet counters amongst you, I ordered some replacement rocker cover dome nuts, as the ones on my bike were a little tarnished (not quite rusty) as you can see below...



but the ones that turned up from the BSA parts people are different, as you can see, but which ones were fitted in 1970?



I also received my new pistons too...



:bigt

The new dome ones, never seen that nipple type before. radius all sharp edges round valve cutouts and polish tops on piston crowns before fitting.